1. Field of the Invention
The present invention relates to a keypad coupling apparatus, and more particularly to a keypad coupling apparatus of a portable terminal, which includes a laminated keypad unit arranged on an upper surface of a front case of a portable terminal.
2. Description of the Related Art
In general, the term “portable communication terminals” refer to devices which a user can carry with him/her while communicating with another user wirelessly. Such portable communication devices include Hand-Held Phones (HHPs), CT-2, cellular phones, digital phones, Personal Communication System (PCS) phones, and Personal Digital Assistants (PDAs). Conventional portable terminals may be classified into various types according to their appearance, such as bar-type portable terminals, flip-type portable terminals, and folder-type portable terminals. The above-mentioned conventional portable terminals essentially include an antenna unit, data input/output units, and a data transmitter and receiver. Of course, a keypad is used as the data input unit, on which a user can press keys with his/her fingers to input data. The keypad used for inputting data includes a plurality of keys.
Hereinafter, the configuration of the bar-type portable terminal including a keypad and a liquid crystal display (LCD) unit will be described. As shown in FIG. 1, the bar-type portable terminal includes a single housing 1, a keypad 2, and an LCD unit 3. The keypad 2 and LCD unit 3 are arranged on a single housing 1. Further, the bar-type portable terminal includes a speaker unit 4 mounted over the LCD unit 3, and a microphone unit 5 disposed at a lower portion of the keypad 2.
The single housing 1 includes a front case 1a and a rear case 1b. The microphone unit 5 is soldered to a printed circuit board 6 mounted in the single housing 1.
A plurality of dome switches 6a is arranged on the printed circuit board 6.
A mounting space 7 for the microphone unit 5 is defined by the front case 1a and the rear case 1b. 
As shown in FIG. 2, the keypad 2 is assembled with the front case 1a in such a manner of coupling the keypad 2 to a back surface of the front case 1a so as to be coupled with fixing ribs 1c formed in the front case 1a. The keypad 2 is exposed to the outside through keyholes 1d formed in the front case 1a. Thus, the keypad 2 is fixed to the front case 1a by means of the fixing ribs 1c. 
In the conventional keypad, however, since a plurality of keys, arranged on the dome switches of the printed circuit board, and the key rubber are sequentially stacked on the back surface of the front case 1a, the keys are inserted in the keyholes 1d and assembled with the front case 1a in order to expose the keys to the outside through the keyholes of the front case. Accordingly, there is a problem in that increasing the thickness of the portable terminal runs counter to the desired slimness and the miniaturization of the portable terminal.
Further, since the portable terminal must have fixing ribs to secure the keypad, this causes an increase in the number of parts. Thus, there are disadvantages in that time to assemble the terminal increases, and manufacturing cost also increases.